remove roles

Author: tinayuangao

src/lib/grid-list/grid-list.ts

@@ -41,7 +41,6 @@ const MD_FIT_MODE = 'fit';
   templateUrl: 'grid-list.html',
   styleUrls: ['grid-list.css'],
   host: {
-    'role': 'list',
     'class': 'mat-grid-list',
   },
   changeDetection: ChangeDetectionStrategy.OnPush,

src/lib/grid-list/grid-tile.ts

@@ -25,7 +25,6 @@ import {coerceToNumber} from './grid-list-measure';
   moduleId: module.id,
   selector: 'md-grid-tile, mat-grid-tile',
   host: {
-    'role': 'listitem',
     'class': 'mat-grid-tile',
   },
   templateUrl: 'grid-tile.html',